In many countries, the average diet does not contain sufficient levels of necessary minerals and nutrients, such as, iron, zinc, iodine, vitamin A or the B vitamins. Iron deficiency is well documented, it is one of the few nutritional deficiencies in the U.S., and it is common in most developing countries. Recent evidence suggests that nutritional zinc deficiency may be common among the people of many developing countries where they subsist on diets of plant origin (e.g. cereal and legume). Marginal mineral deficiencies may be widespread even in the U.S. because of self-imposed dietary restrictions, use of alcohol and cereal proteins, and the increasing use of refined foods that decrease the intake of trace minerals.
Many mineral deficiencies can be overcome by taking supplements. Other methods of addressing these deficiencies include increasing the intake of foods naturally containing these minerals or fortifying food and beverage products. Usually, in countries where the people suffer from these deficiencies, the economy is such that providing minerals and vitamins as a supplement is expensive and presents significant distribution logistics problems. In addition, compliance, i.e., having the people take the vitamin and mineral supplements on a daily basis, is a serious problem. Accordingly, the delivery of minerals along with other vitamins and nutrients in a form that has high bioavailability and at the same time a non-objectionable taste and appearance, and in a form that would be consumed by a high proportion of the population at risk is desirable.
Vitamin and mineral fortified beverages and foods are known. Although substantial progress has been made in reducing iron deficiency by fortifying products such as infant formulas, breakfast cereals and chocolate drink powders, the formulations require milk that is often not available or affordable. To address the problem of iron and zinc deficiencies in the general population, efforts have been directed to formulating fruit-flavored dry beverage mixes supplemented with nutritional amounts (i.e., at least 5% of the USRDI) of zinc and iron with or without vitamins. Many fruit-flavored powdered beverages contain vitamins and/or minerals but seldom contain both zinc and iron at any significant level, see for example, Composition of Foods: Beverages, Agriculture Handbook No. 8 Series, Nutrition Monitoring Division, pgs 115–153.
There are well-recognized problems associated with adding both vitamins and minerals to beverages. Zinc supplements tend to have an objectionable taste, cause distortion of taste and cause mouth irritation, see for example U.S. Pat. No. 4,684,528 (Godfrey), issued Aug. 4, 1987. Iron supplements tend to discolor foodstuff, or to be organoleptically unsuitable. Moreover, it is particularly difficult to formulate products containing minerals and, in particular, mixtures of bioavailable iron and zinc. These minerals not only affects the organoleptic and aesthetic properties of beverages, but also undesirably affects the nutritional bioavailability of the minerals themselves and the stability of vitamins and flavors.
Several problems exist with delivering a mixture of minerals with or without vitamins in a beverage mix. A few of the problems are choosing mineral compounds which are organoleptically acceptable, bioavailable, cost effective and safe. For example, the water soluble iron and zinc compounds, which are the most bioavailable cause unacceptable metallic aftertaste and flavor changes. In addition, the soluble iron complexes often cause unacceptable color changes. Even further, the iron complexes themselves are often colored. This makes formulating a dry powder that has a uniform color distribution in the mix more difficult. Often the reconstituted beverage does not have a suitable color identifiable with the flavoring agent. If the color of the powder, reconstituted beverage or flavor of the beverage is substantially altered, the beverage will not be consumed. Color and taste are key to consumer acceptance.
Many iron sources that have been successful commercially, have been found to be unsatisfactory for use herein. For example, U.S. Pat. No. 4,786,578 (Nakel et al), issued November 1988, relates to the use of iron-sugar complexes suitable for supplementing fruit beverages. While this supplement may produce an acceptable taste in certain fruit flavored beverages, the supplement causes discoloration and consumer detectable differences in some colored beverages. Iron sources typically used to fortify chocolate milk were also found undesirable due to color problems and/or flavor problems.
It has further been found that iron is more bioavailable if administered in the form of chelates wherein the chelating ligands are amino acids or protein hydrolysates. See, for example, U.S. Pat. No. 3,969,540 (Jensen), issued Jul. 13, 1976 and U.S. Pat. No. 4,020,158 (Ashmead), issued Apr. 26, 1977. These chelated iron compounds are known in the art by various names such as iron proteinates, iron amino acid chelates and peptide or polypeptide chelates. These will be referred to herein simply as “amino acid chelated irons.” A particularly desirable amino acid chelated iron is FERROCHEL made by Albion Laboratories. FERROCHEL is a free flowing, fine granular powder that provides a high bioavailable source of ferrous iron that is typically complexed or chelated with the amino acid glycine.
Unfortunately, it has also been found that FERROCHEL, when added to water or other aqueous solutions, imparts relatively quickly a deep rusty yellow color. Such a color can change the color appearance the food or beverage to which FERROCHEL has been added. In the case of many foods and beverages, this color change would be unacceptable. It has been found that FERROCHEL causes unacceptable off-color development in various foods and beverages by interacting with dietary components such as the polyphenols and flavonoids. Furthermore, by accelerating the oxidative rancidity of fats and oils, FERROCHEL (like ferrous sulfate) has been found to cause off-flavor in foods and beverages.
One solution to delivering a mineral-fortified beverage is disclosed in PCT Publication WO 98/48648 (The Procter & Gamble Company), published Nov. 5, 1998, which teaches a dry free-flowing beverage composition that when reconstituted with water has a desirable color and is free of undesirable aftertaste. The dry free-flowing beverage composition contains from about 5% to about 100% of the USRDI of iron, optionally from about 5% to about 100% of the USRDI of zinc, from about 0.001% to about 0.5% of a coloring agent, and from about 0.001% to about 10% of a flavoring agent. An edible acid sufficient to lower the pH to between 3 and 4.5 in the finished beverage is added. As can be appreciated, some of the additives are nutrients, while others are used to mask the taste and off-color caused by adding minerals to an aqueous solution.
An even greater challenge has been faced in providing a mineral fortified drinking water that contains a bioavailable source of iron or zinc mineral. A drinking water, as opposed to a beverage, should contain water as its main ingredient, and which should have the taste and appearance of pure water. Fortification of drinking water with soluble, stable and bioavailable minerals (e.g. iron, zinc) has been a challenge. For instance, when the soluble form of iron (ferrous iron) is added to regular water, it rapidly oxidizes to the insoluble trivalent form, which is ferric iron. Subsequently, the ferric iron combines with hydroxide ions to form iron hydroxide (yellow colored), which later converts to ferric oxide, a red, powdery precipitate called “rust.” Thus, it is well known fact that natural water not only oxidizes iron from ferrous to ferric moieties, but also causes (a) the development of undesirable color (yellowish-rusty), (b) poor solubility demonstrated by precipitation and increased turbidity, (c) compromised bioavailability and (b) co-precipitation of other minerals (e.g. zinc, magnesium, calcium) and phosphate.
The behavior of such nutritionally important minerals in natural water (e.g. lakes, streams, rivers and oceans) is due to the oxidizing nature of the natural water. Most fresh water and lakes have a pH range from pH 5 to about 9. Furthermore, they contain not only dissolved oxygen but also other electron accepting species (iron-oxidizing) such as nitrates, manganese (IV), chloride ions. Both the pH range and the presence of the electron accepting species makes natural water an oxidizing media. Thus, it favors poor solubility, off-color development and compromised bioavailability and stability. In fact, the ability (tendency) of natural water to act as an oxidizing media is determined by measuring the Redox potential (Eh) in millivolts (mV). The redox potential for the different species of iron is defined by (a) Eh-pH diagram and (b) Nernest's equation: Eh=Eo+0.059/n log [oxidized species]/[reduced species], where Eh=observed electrode potential, Eo=standard electrode potential, n=number of electrons transferred. Under normal condition, water has relatively high redox potential (>300 mV), which is an indicator of highly oxidizing environment. This is primarily due to the presence of various electron acceptors (oxidizing agents), which include ozone, chlorine, oxygen, nitrates and manganese (1V).
Hence, there is a tendency for iron to turn rusty and precipitate as a result of the oxidizing nature of the water, and to develop a metallic off-taste that is attributed to free iron ions in the water. Since drinking waters should not have perceptible flavors or colors, the development of unacceptable iron coloration, poor solubility, or metallic taste in a drinking water cannot be masked over.
Attempts to provide an iron-containing drinking water in the past have shown limited success. FR Patent publication 2,461,463, published Feb. 6, 1981, discloses a procedure for preparing and stabilizing an iron-containing mineral water by adding an ascorbic acid, or salt thereof, reducing agent, where the weight ratio of ascorbic acid to ferrous ion is from about 2.5–6.5. The reducing agent is added to reduce any ferric ions to the ferrous state, which was believed to be the active bioavailable state of iron.
Further, German Patent No. 19,628,575, published Jan. 29, 1998, discloses drinking water or mineral water such as coffee, fruit teas or soft drinks, containing ferrous iron and an excess of organic or inorganic dietary acids to reduce the water pH to the range of 2–5. Iron gluconate and iron sulfate were disclosed as the added iron source. The resulting acid flavor of these waters was then neutralized by the addition of flavors, sugar and/or sweetener.
Accordingly, there exists a need for a water composition fortified with a nutritional amount of minerals, that is, metal ions, which is palatable and does not have a disagreeable aftertaste while preserving the bioavailability of the metal ions. It is preferred that these compositions have no metallic taste or aftertaste, without the use of any flavor or sweetener. It is desired that these compositions have an acceptable clarity and color, and preferably they are clear and colorless. Moreover, there is a need for water compositions that have a reducing environment, that is, low redox potential values. This would allow for the production of a water composition that maintains metal ions substantially in their reduced state through redox modulation, and wherein the water comprises low levels of the most dominant redox-active species, dissolved oxygen. These and many more advantages are provided by the present invention.